high performance application webserver in C/C++

Question

Is there any high performance (ideally evented and open source) web server in C or C++?

I'd like to be able to use it in that it calls a method/function in my application with a filled out HTTP Request class/struct, and then I can return a filled out HTTP Response class/struct to it.

If it isn't open source, I'd need built in support for long-polling connections, keep-alive, etc—otherwise, I think that I can add these things myself.

If you don't know of any such servers available, would you recommend writing my own web server to fit the task? It cannot be file-based, and must be written in high-performance C/C++.

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Edit: I'm thinking something like the Ruby Mongrel for C, if that helps.

Answer 1

I had the very same requirements for my job, so I evaluated a number of solutions: mongoose, libmicrohttpd, libevent. And I also was thinking about writing nginx modules. Here is the summary of my findings:

nginx

nginx project page

I love this server and use it a lot. Its performance and resource usage is much better than that of Apache, which I also still use but plan migrating to nginx.

• Very good tunable performance. Rich functionality. Portability.
• Module API is not documented and seems to be very verbose. See this nginx hello world module as example.
• Nginx does not use threads but uses multiple processes. This makes writing modules harder, need to learn nginx API for shared memory, etc.

mongoose

mongoose project page

• All server's code is in single mongoose.c file (about 130K), no dependencies. This is good.
• One thread per connection, so if you need concurrency you've got to configure lots of threads, ie. high RAM usage. Not too good.
• Performance is good, although not exceptional.
• API is simple but you have to compose all response HTTP headers yourself, ie. learn HTTP protocol in detail.

libmicrohttpd

libmicrohttpd project page

• Official GNU project.
• Verbose API, seems awkward to me, although much more simple than writing nginx modules.
• Good performance in keep-alive mode (link to my benchmarks below), not so good without keep-alive.

libevent

libevent project page

Libevent library has built-in web server called evhttp.

• It is event based, uses libevent for that.
• Easy API. Constructs HTTP headers automatically.
• Officially single-threaded. This is major disadvantage. I've found a hack, which makes several instances of evhttp run simultaneously accepting connections from the same socket. Not sure if it is all safe and robust.
• Performance of single-threaded evhttp is surprisingly poor. Multi-threaded hack works better, but still not good.

G-WAN

G-WAN project is not open source, but I'd like to say a few words about it.

• Very good performance, low memory usage, 150 KB executable.
• Very convenient 'servlet' deployment: just copy .c file into csp directory, and running server automatically compiles it. Code modifications also compiled on the fly.
• Simple API. Although constrained in some ways. Rich functionality (json, key-value store, etc.).
• Unstable. I had segfaults on static files. Hangs on some sample scripts. (Experienced on clean install. Never mixed files of different versions).
• Only 32-bit binary (not anymore).

So as you can see, none of existing alternatives have fully satisfied me. So I have developed my own server, which is ...

NXWEB

NXWEB project page

Feature highlights:

• Very good performance; see benchmarks on project page
• Can serve tens of thousands concurrent requests
• Small memory footprint
• Multi-threaded model designed to scale
• Exceptionally light code base
• Simple API
• Decent HTTP protocol handling
• Keep-alive connections
• SSL support (via GNUTLS)
• HTTP proxy (with keep-alive connection pooling)
• Non-blocking sendfile support (with configurable small file memory cache; gzip pre-encoded file serving)
• Modular design for developers
• Can be run as daemon; relaunches itself on error
• Open source

Limitations:

• Depends on libev library (not anymore)
• Only tested on Linux

Answer 2

I would suggest to write a FastCGI executable that can be used with many high performance web servers (even closed source ones).